A technique of forming a β-Ga2O3 single crystal film on a β-Ga2O3-based substrate by epitaxial crystal growth using the MBE (Molecular Beam Epitaxy) method is conventionally known (see, e.g., PTL 1).
According to PTL 1, the β-Ga2O3 single crystal film can be grown at a high growth rate by the MBE method when the plane orientation of the principal surface of the β-Ga2O3-based substrate is adjusted to a predetermined plane orientation.